The invention relates to an articulated bearing for the articulated transfer of heavy loads to a support, in particular to brace a bridge superstructure on a bearing pad, with a bearing pot, which contains an incompressible, deformable pressurized material and rests on the support, said bearing pot comprising a pot bottom and a pot wall, and with a cover, which receives the load to be braced, rests on the pressurized material and is sealed with respect to the pot wall.
Such articulated bearings serve to transfer freely and easily large loads to a support. The bearings have to transfer both vertical and horizontal loads, yet allow tilting movements around arbitrary horizontal axes during most applications. These tilting joints are employed especially during bridge construction in order to support the superstructure on a bearing pad.
In the known articulated bearings which are also called "neo pot bearings" or "rubber pot bearings" the deformable pressurized material is a plastic material, which is enveloped on all sides by the bearing pot and the cover. The cover is braced in the vertical direction against the deformable pressurized material and in the horizontal direction against the pot wall. The pot wall is stressed by both the lateral pressure of the pressurized material and the external horizontal forces exerted through the cover. This horizontal stress necessitates that the pot wall and the connecting region at the pot bottom be quite thick.
Therefore, the object of the invention is to design an articulated bearing of the aforementioned class in such a manner that the wall of the bearing pot can be designed as small as possible.
This problem is solved according to the invention by further connecting the pot to the cover with a journal-and-recess connection and positioning the journal within only a portion of the height of the recess to form therein a vertical gap. The gap is also filled with the pressurized medium that occupies the main space formed between the cover and pot for maximizing the supporting area of the pressurized medium. Communication is provided between the gap and the main space for equalizing pressure therebetween.
Since the horizontal forces are transferred by means of the central bearing, the pot wall is relieved of these possibly very high horizontal forces and has only to absorb the side pressure of the deformable pressurized material. Apart from the relatively low sealing forces, no horizontal forces are transferred from the cover to the pot wall.
Since the horizontal forces are not introduced into the pot bottom in the connecting region of the pot wall, but rather in the middle of the pot bottom, the entire bearing pot can be designed with relatively small outer dimensions and--at least in the pot wall and the outer region of the pot bottom--with relatively low wall thickness, since even the flexural stresses in the region where the pot wall is connected to the pot bottom are relatively low.
Preferably the thickness of the pot bottom increases starting from the pot wall and going in the direction of the central horizontal bearing in order to introduce the horizontal forces from the horizontal bearing into the pot bottom without necessitating an increase in the outer dimensions of the articulated bearing.
The articulated bearing can be filled with the pressurized fluid as the pressurized material by means of a closable port in the pot wall or in the cover.
If a tilting Option is desired on all sides, the bearing journal is rotationally symmetrical and the bearing recess is a central bearing borehole. If, on the other hand, a tilting motion is required only around a single horizontal bearing axis, then the bearing journal according to the invention is a strip extending in essence over the width of the bearing pot, and the bearing recess is a bearing groove, with which this strip engages.
It has been demonstrated to be especially advantageous to provide in another embodiment of the inventive idea the bearing journal with a crowned outer surface, which forms preferably a spherical surface and which is braced horizontally against a cylindrical bore wall of the bearing borehole. Since virtually no vertical displacement can occur owing to the incompressibility of the deformable pressurized material, the bearing journal is stressed only by the hertzian compressive strains in the region of contact with the cylindrical bore wall of the bearing borehole.
Since there are no elements serving to the transfer horizontal forces between the circumference of the cover and the pot wall outside the pot seal, the construction of the articulated bearing is simplified and the assembly of the pot seal and articulated bearing become significantly easier. The pot seal lies in a groove and is self-sealing as a consequence of the lip resting against the pot wall.